mtdoops.c

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/*
 * MTD Oops/Panic logger
 *
 * Copyright © 2007 Nokia Corporation. All rights reserved.
 *
 * Author: Richard Purdie <[email protected]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/console.h>
#include <linux/vmalloc.h>
#include <linux/workqueue.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/mtd/mtd.h>
#include <linux/kmsg_dump.h>

/* Maximum MTD partition size */
#define MTDOOPS_MAX_MTD_SIZE (8 * 1024 * 1024)

#define MTDOOPS_KERNMSG_MAGIC 0x5d005d00
#define MTDOOPS_HEADER_SIZE   8

static unsigned long record_size = 4096;
module_param(record_size, ulong, 0400);
MODULE_PARM_DESC(record_size,
        "record size for MTD OOPS pages in bytes (default 4096)");

static char mtddev[80];
module_param_string(mtddev, mtddev, 80, 0400);
MODULE_PARM_DESC(mtddev,
        "name or index number of the MTD device to use");

static int dump_oops = 1;
module_param(dump_oops, int, 0600);
MODULE_PARM_DESC(dump_oops,
        "set to 1 to dump oopses, 0 to only dump panics (default 1)");

static struct mtdoops_context {
    struct kmsg_dumper dump;

    int mtd_index;
    struct work_struct work_erase;
    struct work_struct work_write;
    struct mtd_info *mtd;
    int oops_pages;
    int nextpage;
    int nextcount;
    unsigned long *oops_page_used;

    void *oops_buf;
} oops_cxt;

static void mark_page_used(struct mtdoops_context *cxt, int page)
{
    set_bit(page, cxt->oops_page_used);
}

static void mark_page_unused(struct mtdoops_context *cxt, int page)
{
    clear_bit(page, cxt->oops_page_used);
}

static int page_is_used(struct mtdoops_context *cxt, int page)
{
    return test_bit(page, cxt->oops_page_used);
}

static void mtdoops_erase_callback(struct erase_info *done)
{
    wait_queue_head_t *wait_q = (wait_queue_head_t *)done->priv;
    wake_up(wait_q);
}

static int mtdoops_erase_block(struct mtdoops_context *cxt, int offset)
{
    struct mtd_info *mtd = cxt->mtd;
    u32 start_page_offset = mtd_div_by_eb(offset, mtd) * mtd->erasesize;
    u32 start_page = start_page_offset / record_size;
    u32 erase_pages = mtd->erasesize / record_size;
    struct erase_info erase;
    DECLARE_WAITQUEUE(wait, current);
    wait_queue_head_t wait_q;
    int ret;
    int page;

    init_waitqueue_head(&wait_q);
    erase.mtd = mtd;
    erase.callback = mtdoops_erase_callback;
    erase.addr = offset;
    erase.len = mtd->erasesize;
    erase.priv = (u_long)&wait_q;

    set_current_state(TASK_INTERRUPTIBLE);
    add_wait_queue(&wait_q, &wait);

    ret = mtd_erase(mtd, &erase);
    if (ret) {
        set_current_state(TASK_RUNNING);
        remove_wait_queue(&wait_q, &wait);
        printk(KERN_WARNING "mtdoops: erase of region [0x%llx, 0x%llx] on \"%s\" failed\n",
               (unsigned long long)erase.addr,
               (unsigned long long)erase.len, mtddev);
        return ret;
    }

    schedule();  /* Wait for erase to finish. */
    remove_wait_queue(&wait_q, &wait);

    /* Mark pages as unused */
    for (page = start_page; page < start_page + erase_pages; page++)
        mark_page_unused(cxt, page);

    return 0;
}

static void mtdoops_inc_counter(struct mtdoops_context *cxt)
{
    cxt->nextpage++;
    if (cxt->nextpage >= cxt->oops_pages)
        cxt->nextpage = 0;
    cxt->nextcount++;
    if (cxt->nextcount == 0xffffffff)
        cxt->nextcount = 0;

    if (page_is_used(cxt, cxt->nextpage)) {
        schedule_work(&cxt->work_erase);
        return;
    }

    printk(KERN_DEBUG "mtdoops: ready %d, %d (no erase)\n",
           cxt->nextpage, cxt->nextcount);
}

/* Scheduled work - when we can't proceed without erasing a block */
static void mtdoops_workfunc_erase(struct work_struct *work)
{
    struct mtdoops_context *cxt =
            container_of(work, struct mtdoops_context, work_erase);
    struct mtd_info *mtd = cxt->mtd;
    int i = 0, j, ret, mod;

    /* We were unregistered */
    if (!mtd)
        return;

    mod = (cxt->nextpage * record_size) % mtd->erasesize;
    if (mod != 0) {
        cxt->nextpage = cxt->nextpage + ((mtd->erasesize - mod) / record_size);
        if (cxt->nextpage >= cxt->oops_pages)
            cxt->nextpage = 0;
    }

    while ((ret = mtd_block_isbad(mtd, cxt->nextpage * record_size)) > 0) {
badblock:
        printk(KERN_WARNING "mtdoops: bad block at %08lx\n",
               cxt->nextpage * record_size);
        i++;
        cxt->nextpage = cxt->nextpage + (mtd->erasesize / record_size);
        if (cxt->nextpage >= cxt->oops_pages)
            cxt->nextpage = 0;
        if (i == cxt->oops_pages / (mtd->erasesize / record_size)) {
            printk(KERN_ERR "mtdoops: all blocks bad!\n");
            return;
        }
    }

    if (ret < 0) {
        printk(KERN_ERR "mtdoops: mtd_block_isbad failed, aborting\n");
        return;
    }

    for (j = 0, ret = -1; (j < 3) && (ret < 0); j++)
        ret = mtdoops_erase_block(cxt, cxt->nextpage * record_size);

    if (ret >= 0) {
        printk(KERN_DEBUG "mtdoops: ready %d, %d\n",
               cxt->nextpage, cxt->nextcount);
        return;
    }

    if (ret == -EIO) {
        ret = mtd_block_markbad(mtd, cxt->nextpage * record_size);
        if (ret < 0 && ret != -EOPNOTSUPP) {
            printk(KERN_ERR "mtdoops: block_markbad failed, aborting\n");
            return;
        }
    }
    goto badblock;
}

static void mtdoops_write(struct mtdoops_context *cxt, int panic)
{
    struct mtd_info *mtd = cxt->mtd;
    size_t retlen;
    u32 *hdr;
    int ret;

    /* Add mtdoops header to the buffer */
    hdr = cxt->oops_buf;
    hdr[0] = cxt->nextcount;
    hdr[1] = MTDOOPS_KERNMSG_MAGIC;

    if (panic) {
        ret = mtd_panic_write(mtd, cxt->nextpage * record_size,
                      record_size, &retlen, cxt->oops_buf);
        if (ret == -EOPNOTSUPP) {
            printk(KERN_ERR "mtdoops: Cannot write from panic without panic_write\n");
            return;
        }
    } else
        ret = mtd_write(mtd, cxt->nextpage * record_size,
                record_size, &retlen, cxt->oops_buf);

    if (retlen != record_size || ret < 0)
        printk(KERN_ERR "mtdoops: write failure at %ld (%td of %ld written), error %d\n",
               cxt->nextpage * record_size, retlen, record_size, ret);
    mark_page_used(cxt, cxt->nextpage);
    memset(cxt->oops_buf, 0xff, record_size);

    mtdoops_inc_counter(cxt);
}

static void mtdoops_workfunc_write(struct work_struct *work)
{
    struct mtdoops_context *cxt =
            container_of(work, struct mtdoops_context, work_write);

    mtdoops_write(cxt, 0);
}

static void find_next_position(struct mtdoops_context *cxt)
{
    struct mtd_info *mtd = cxt->mtd;
    int ret, page, maxpos = 0;
    u32 count[2], maxcount = 0xffffffff;
    size_t retlen;

    for (page = 0; page < cxt->oops_pages; page++) {
        if (mtd_block_isbad(mtd, page * record_size))
            continue;
        /* Assume the page is used */
        mark_page_used(cxt, page);
        ret = mtd_read(mtd, page * record_size, MTDOOPS_HEADER_SIZE,
                   &retlen, (u_char *)&count[0]);
        if (retlen != MTDOOPS_HEADER_SIZE ||
                (ret < 0 && !mtd_is_bitflip(ret))) {
            printk(KERN_ERR "mtdoops: read failure at %ld (%td of %d read), err %d\n",
                   page * record_size, retlen,
                   MTDOOPS_HEADER_SIZE, ret);
            continue;
        }

        if (count[0] == 0xffffffff && count[1] == 0xffffffff)
            mark_page_unused(cxt, page);
        if (count[0] == 0xffffffff)
            continue;
        if (maxcount == 0xffffffff) {
            maxcount = count[0];
            maxpos = page;
        } else if (count[0] < 0x40000000 && maxcount > 0xc0000000) {
            maxcount = count[0];
            maxpos = page;
        } else if (count[0] > maxcount && count[0] < 0xc0000000) {
            maxcount = count[0];
            maxpos = page;
        } else if (count[0] > maxcount && count[0] > 0xc0000000
                    && maxcount > 0x80000000) {
            maxcount = count[0];
            maxpos = page;
        }
    }
    if (maxcount == 0xffffffff) {
        cxt->nextpage = 0;
        cxt->nextcount = 1;
        schedule_work(&cxt->work_erase);
        return;
    }

    cxt->nextpage = maxpos;
    cxt->nextcount = maxcount;

    mtdoops_inc_counter(cxt);
}

static void mtdoops_do_dump(struct kmsg_dumper *dumper,
                enum kmsg_dump_reason reason)
{
    struct mtdoops_context *cxt = container_of(dumper,
            struct mtdoops_context, dump);

    /* Only dump oopses if dump_oops is set */
    if (reason == KMSG_DUMP_OOPS && !dump_oops)
        return;

    kmsg_dump_get_buffer(dumper, true, cxt->oops_buf + MTDOOPS_HEADER_SIZE,
                 record_size - MTDOOPS_HEADER_SIZE, NULL);

    /* Panics must be written immediately */
    if (reason != KMSG_DUMP_OOPS)
        mtdoops_write(cxt, 1);

    /* For other cases, schedule work to write it "nicely" */
    schedule_work(&cxt->work_write);
}

static void mtdoops_notify_add(struct mtd_info *mtd)
{
    struct mtdoops_context *cxt = &oops_cxt;
    u64 mtdoops_pages = div_u64(mtd->size, record_size);
    int err;

    if (!strcmp(mtd->name, mtddev))
        cxt->mtd_index = mtd->index;

    if (mtd->index != cxt->mtd_index || cxt->mtd_index < 0)
        return;

    if (mtd->size < mtd->erasesize * 2) {
        printk(KERN_ERR "mtdoops: MTD partition %d not big enough for mtdoops\n",
               mtd->index);
        return;
    }
    if (mtd->erasesize < record_size) {
        printk(KERN_ERR "mtdoops: eraseblock size of MTD partition %d too small\n",
               mtd->index);
        return;
    }
    if (mtd->size > MTDOOPS_MAX_MTD_SIZE) {
        printk(KERN_ERR "mtdoops: mtd%d is too large (limit is %d MiB)\n",
               mtd->index, MTDOOPS_MAX_MTD_SIZE / 1024 / 1024);
        return;
    }

    /* oops_page_used is a bit field */
    cxt->oops_page_used = vmalloc(DIV_ROUND_UP(mtdoops_pages,
            BITS_PER_LONG) * sizeof(unsigned long));
    if (!cxt->oops_page_used) {
        printk(KERN_ERR "mtdoops: could not allocate page array\n");
        return;
    }

    cxt->dump.max_reason = KMSG_DUMP_OOPS;
    cxt->dump.dump = mtdoops_do_dump;
    err = kmsg_dump_register(&cxt->dump);
    if (err) {
        printk(KERN_ERR "mtdoops: registering kmsg dumper failed, error %d\n", err);
        vfree(cxt->oops_page_used);
        cxt->oops_page_used = NULL;
        return;
    }

    cxt->mtd = mtd;
    cxt->oops_pages = (int)mtd->size / record_size;
    find_next_position(cxt);
    printk(KERN_INFO "mtdoops: Attached to MTD device %d\n", mtd->index);
}

static void mtdoops_notify_remove(struct mtd_info *mtd)
{
    struct mtdoops_context *cxt = &oops_cxt;

    if (mtd->index != cxt->mtd_index || cxt->mtd_index < 0)
        return;

    if (kmsg_dump_unregister(&cxt->dump) < 0)
        printk(KERN_WARNING "mtdoops: could not unregister kmsg_dumper\n");

    cxt->mtd = NULL;
    flush_work(&cxt->work_erase);
    flush_work(&cxt->work_write);
}


static struct mtd_notifier mtdoops_notifier = {
    .add    = mtdoops_notify_add,
    .remove = mtdoops_notify_remove,
};

static int __init mtdoops_init(void)
{
    struct mtdoops_context *cxt = &oops_cxt;
    int mtd_index;
    char *endp;

    if (strlen(mtddev) == 0) {
        printk(KERN_ERR "mtdoops: mtd device (mtddev=name/number) must be supplied\n");
        return -EINVAL;
    }
    if ((record_size & 4095) != 0) {
        printk(KERN_ERR "mtdoops: record_size must be a multiple of 4096\n");
        return -EINVAL;
    }
    if (record_size < 4096) {
        printk(KERN_ERR "mtdoops: record_size must be over 4096 bytes\n");
        return -EINVAL;
    }

    /* Setup the MTD device to use */
    cxt->mtd_index = -1;
    mtd_index = simple_strtoul(mtddev, &endp, 0);
    if (*endp == '\0')
        cxt->mtd_index = mtd_index;

    cxt->oops_buf = vmalloc(record_size);
    if (!cxt->oops_buf) {
        printk(KERN_ERR "mtdoops: failed to allocate buffer workspace\n");
        return -ENOMEM;
    }
    memset(cxt->oops_buf, 0xff, record_size);

    INIT_WORK(&cxt->work_erase, mtdoops_workfunc_erase);
    INIT_WORK(&cxt->work_write, mtdoops_workfunc_write);

    register_mtd_user(&mtdoops_notifier);
    return 0;
}

static void __exit mtdoops_exit(void)
{
    struct mtdoops_context *cxt = &oops_cxt;

    unregister_mtd_user(&mtdoops_notifier);
    vfree(cxt->oops_buf);
    vfree(cxt->oops_page_used);
}


module_init(mtdoops_init);
module_exit(mtdoops_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Richard Purdie <[email protected]>");
MODULE_DESCRIPTION("MTD Oops/Panic console logger/driver");